Today I’ve been working together with my colleague Irwin at a customer.
We needed to do a small inventory off the active directory, amongs that was a list of user properties.
When we used Get-ADUser, we got an error:

This was caused because the customer had custom attributes included in their AD schema that didn’t follow the datetime guidelines. Get-ADUser couldn’t handle this, since it converts a string value based on the format to a datetime object.
So, what to do… what to do?
When something like this happens, I generally just go to a higher level… in this case: The schema.